Answer:
Mango slices, like many fruits, are made up of cells that are surrounded by a selectively permeable membrane. This means that some molecules can pass through the membrane while others cannot.
When mango slices are placed in water, the concentration of water molecules outside the cells is higher than the concentration of water molecules inside the cells. This creates a concentration gradient, and water molecules move from the area of higher concentration (outside the cells) to the area of lower concentration (inside the cells) through a process called osmosis.
As the water molecules move into the cells, the cells become filled with water and begin to swell up. This is because the cell membrane is flexible and can expand to accommodate the extra water. The process continues until the concentration of water molecules inside and outside the cells is equalized, at which point the cells stop swelling.
In some cases, the swelling of fruit cells can cause the fruit to become softer or even burst open. This is why some fruits, such as watermelon and cucumbers, are often salted before being eaten - the salt draws water out of the cells and helps to prevent them from bursting.